This invention relates to an improved multiplex system which is coordinated with the power bus system and the fuse block of a vehicle in order to reduce the cost and improve the performance of the multiplex system.
Conventionally, vehicles such as automobiles include an electrical power distribution system which includes a fuse block from which a number of power buses radiate. Fuses are provided in the fuse block to provide overload protection for individual ones of the power buses. The fuse block is conventionally mounted either near the instrument panel or in the engine compartment of the vehicle. Lobe U.S. Pat. No. 4,555,638 describes one example of such a prior art fuse block.
There is an increasing interest in utilizing multiplex systems to reduce the cost and number of cables required to transmit control signals between switches distributed around the vehicle and the loads controlled by the switches. The U.S. patents listed below describe several approaches to such multiplex systems.
______________________________________ U.S. Pat. No. Inventor(s) ______________________________________ 3,651,454 Venema et al. 4,156,151 Borroni 4,176,250 Berglind 4,232,231 Reed 4,463,341 Iwasaki 4,538,262 Sinniger et al. 4,554,461 Oho et al. 4,584,487 Hesse et al. 4,594,571 Neuhaus et al. ______________________________________
Berglind U.S. Pat. No. 4,176,250 describes a time division multiplex system for an automobile which utilizes a transmitter module located in the left front door of the automobile. This transmitter module transmits information to receiver modules which are interconnected by means of a data line and are located in the passenger doors and beneath the front seat of the automobile. The remaining patents listed above, though they relate to multiplex systems for vehicles, do not discuss the location of the controller. All of the multiplex systems of these patents are independent of and not coordinated in the manner described below with the power distribution system of the vehicle. As pointed out in detail below, for these reasons these multiplex systems do not take advantage of important economies and improvements in reliability that can be achieved by properly coordinating the power distribution system and the multiplex system of the vehicle.